Herbicidal agents based on heteroaryloxyacetamides and metribuzin

ABSTRACT

The novel herbicidal active ingredient combinations consisting of 
     (1) a heteroaryloxyacetamide of the general formula (I) ##STR1## in which Het, R 1  and R 2  have the meanings given in the description (=active ingredients of group 1) and 
     (2) a known herbicidal active ingredient from group 2, which comprises the substance classes consisting of the phenyl- and benzothiazolylureas, dinitroanilines, triazines, triazinones, sulphonylureas, imidazolinones, pyridinecarboxamides and diphenyl ethers, 
     exhibit synergistie effects in certain weight ratios and can be used as selective herbicides in various crop plants (for example wheat, barley and maize). 
     Synergistic active ingredient combinations of N-iso-propyl-N-(4-fluorophenyl)-(5-trifluoromethyl -1,3,4-thiadiazol-2-yl-oxy)-acetamide and isoproturon, methabenzthiazuron or metribuzine may be mentioned as examples.

This application has been filed under 35 USC 371 from internationalapplication PCT/EP93/01732, filed Jul. 5, 1993.

This application has been filed under 35 USC 371 from internationalapplication PCT/EP93/01732, filed Jul. 5, 1993 and published asWO94/02014 Feb. 3, 1994.

The invention relates to novel herbicidal, synergistic combinations ofthe known heteroaryloxyacetamides on the one hand and further knownherbicides belonging to other classes of substances on the other hand,which can be particularly advantageously used for selectively combattingweeds in various crops/plants.

The patent specifications cited below describe heteroaryloxyacetamideswhich are preferentially effective against monocotyledon weeds (=grassweeds) but also against some dicotyledon weeds. They exhibit practicallyexclusively soil activity and only slight activity via the foliage, andsome of them have a high selectivity in mono- and dicotyledon cropplants, such as cereals, maize, rice, soya bean and cotton [cf. forexample EP-A 5 501 (=U.S. Pat. No. 4,509,971 and U.S. Pat. No.4,833,243); EP-A 18 497 (=U.S. Pat. No. 4,645,525 and U.S. Pat. No.4,756,741); EP-A 29 171 (=U.S. Pat. No. 4,408,055); EP-A 94 514 (=U.S.Pat. No. 4,585,471); EP-A 100 044 (=U.S. Pat. No. 4,549,899); EP-A 100045 (=U.S. Pat. No. 4,540,430); EP-A 161 602 (=U.S. Pat. No. 4,784,682);EP-A195 237 (=U.S. Pat. No. 4,788,291); DE-A 3 724 467; EP-A 348 734(=U.S. Pat. No. 4,988,380); EP-A 348 737 (=U.S. Pat. Nos. 4,968,342 and5,090,991); DE-A 4 113 421 and DE-A 4 137 827, as well as WO 91/06544].

Surprisingly, biological experimentation has now uncovered a number ofknown herbicidally active compounds from the classes of the phenyl- andbenzthiazolyl-ureas, imidazolinones, pyridinecarboxamides and diphenylethers which, when used together with the abovementionedheteroaryloxyacetamides, possess extremely synergistic properties withregard to the effectiveness against weeds and can be used particularlyadvantageously, that is to say as broadly effective combinationpreparations, for selectively combatting weeds--both monocotyledon anddicotyledon weeds, by the preemergence and postemergence methods--inmonocotyledon and dicotyledon crop plants, such as, for example, maize,wheat, barley, rice, soya bean, cotton, beet and peanuts, so that anumber of economically important (problem) weeds and grass weeds can bereliably controlled.

The present invention provides herbicidal synergistic agents,characterised by an effective content of an active ingredientcombination consisting of

(1) a heteroaryloxyacetamide of the general formula (I) ##STR2## inwhich Het represents an optionally substituted heteroaromatic radicalfrom the series consisting of 1,3-thiazol-2-yl, 1,2,4-thiadiazol-2-yl,1,3,4-thiadiazol-2-yl, benzoxazol-2-yl and benzothiazol-2yl.

R¹ represents C₁ -C₄ -alkyl, C₃ -C₄ -alkenyl or C₁ --₄ -alkoxy, each ofwhich is optionally substituted, and

R² represents C₁ -C₄ -alkyl, C₃ -C₄ -alkenyl or phenyl, each of which isoptionally substituted, (=active ingredients of group 1) and

(2) a known herbicidal active ingredient from the group 2 which containsthe compound classes (a) to (i) mentioned below:

(a) N-phenylureas, such as, for example,3-(4-isopropylphenyl)-1,1-dimethylurea (ISOPROTURON),3-(3-chloro-4-methylphenyl)-1,1-dimethylurea (CHLORTOLURON),3-(3,4-dichlorophenyl) -1,1-dimethylurea(DIURON),3-(4-chlorophenyl)-1,1-dimethylurea (MONURON), 3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea (LINURON),3-(4-chlorophenyl)-1-methoxy-1-methyl-urea (MONOLINURON) or3-(3-trifluoromethyl-phenyl) -1,1-dimethylurea (FLUOMETURON);

(b) N-benzthiazolyl-ureas, such as, for example,3-(benzthiazol-2-yl)-1,3-dimethyl-urea (METHABENZTHIAZURON);

(c) 2,6-dinitroanilines, such as, for example,N,N-di-(n-propyl)-2,6-dinitro-4-trifluoromethylaniline (TRIFLURALIN) orN-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitroaniline (PENDIMETHALIN);

(d) s-triazines, such as, for example,2-chloro-4-ethylamino-6-isopropylamino-s-triazine (ATRAZINE),2-chloro-4-(1-cyano-1-methylethyl-amino)-6-ethylamino-s-triazine(CYANAZINE). 2-Chloro-4-ethylamino-6-tert.butylamino-s -triazine(TERBUTHYLAZINE), 2-ethylamino-4-methylthio-6-tert.butylamino-s-triazine (TERBUTRYN)or2-chloro-4,6-bis-(ethylamino)-s-triazine (SIMAZINE);

(e) as-triazinones, such as, for example,4-amino-6-tert.-butyl-3-methylthio-1,2,4-triazin -5-(4H)-one(METRIBUZINE), 3-methyl-4-amino-6-phenyl-1,2,4-triazin-5-(4H)-one(METAMITRON) or 4-amino-6-tert.-butyl-3-ethylthio-1,2,4-triaxin-5(4H)-one (ETHIOZINE);

(f) sulphonylureas, such as, for example,3-(4-methoxy-6-methyl-1,3,5-triazin-2-yl)-1-(2-chlorophenyl)-sulphonylurea(CHLOROSULFURON),3-(4-methoxy-6-methyl-1,3,5-triazin-2-yl)-1-(2-methoxycarbonyl-phenyl)-sulphonylurea(MET-SULFURON);3-(4-methoxy-6-methyl-1,3,5-triazin-2-yl)-1-(2-methoxycarbonyl-thien-3-yl-sulphonylurea)(THIFENSULFURON),3-(4-methoxy-6-methyl-1,3,5-triazin-2-yl)-3-methyl-1-(2-(methoxycarbonyl-phenyl)-sulphonylurea(TRIBENURON);3-(4,6-dimethoxy-pyrimidin-2-yl)-1-(2-methoxycarbonyl-benzyl)-sulphonylurea(BENSULFURON),3-(4-chloro-6-methoxypyrimidin-2-yl)-1-(2-ethoxycarbonyl-phenyl)-sulphonylurea(CHLORIMURON),3-(4,6-dimethoxypyrimidin-2-yl)-1-(3-dimethylaminopyridin-2-yl)-sulphonylurea(NICOSULFURON),3-(4-methoxy-6-methyl-1,3,5-triazin-2-yl)-1-[2-(2-chloroethoxy)-phenyl]-sulphonylurea(TRIASULFURON),3-[4,6-bis-(difluoromethoxy)-pyrimidin-2-yl]-1-(2-methoxy-carbonylphenyl)-sulphonylurea(PRIMISULFURON) or3-(4,6-dimethoxy-pyrimidin-2-yl)-1-(N-methyl-N-methylsulphonyl-amino)-sulphonylurea(AMIDOSULFURON);

(g) imidazolinones, such as, for example,2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylicacid (IMAZAQUIN),2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-pyridinecarboxylicacid (IMAZAPYR) or methyl2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-methyl-benzoate(IMAZAMETHABENZ);

(h) pyridinecarboxamides, such as, for example,N-(2,4-difluorophenyl)-2-(3-trifluoromethyl-phenoxy)-3-pyridinecarboxamide (DIFLUFENICAN); and

(i) diphenyl ethers, such as, for example, 2,4-dichlorophenyl3'-methoxycarbonyl-4'-nitrophenyl ether (BIFENOX),5-(2-chloro-4-tri-fluoromethyl-phenoxy)-2-nitro-benzoic acid(ACIFLUORFEN), [1-(ethoxycarbonyl)-ethyl]5-[2'-chloro-4'-trifluoromethyl-phenoxy]-2-nitro benzoate (LACTOFEN) or5-(2-chloro-4-trifluoro-methyl-phenoxy)-N-methylsulphonyl-2-nitro-benzamide(FOMESAFEN);

(=active ingredients of group 2), in general 0.001 to 1,000 parts byweight of active ingredient of group (2) being used per 1 part by weightof active ingredient of group (1) (that is to say of the formula (I)).

Of particular interest are herbicidal agents according to the inventioncontaining compounds of the stated formula (I) in which

Het represents an optionally substituted 1,3,4-thia-diazol-2-yl radical,

R¹ represents C₁ -C₄ -alkyl and

R² represents optionally substituted phenyl, in combination with anN-phenylurea, an N-benzothiazolylurea or an as-triazinone.

Very particularly preferred herbicidal agents according to the inventioncontain, as a compound of the formula (I),

N-isopropyl-N-(4-fluorophenyl)-5-trifluoromethyl-1,3,4-thiadiazol-2-yl-oxy)-acetamide of the formula(I-1) ##STR3## in combination with

    ______________________________________                                        ISOPROTURON          = (IPU),                                                 METHABENZTHIAZURON   = (MBT) or                                               METRIBUZINE          = (MBZ).                                                 ______________________________________                                    

The compound of the formula (I-1) is known, for example from EP-A 348737 and U.S. Pat. No. 4,968,342. The other active ingredients of thegeneral formula (I) are described in the patent specifications orapplications cited at the outset.

The active ingredients of group (2) are described in "The PesticideManual", British Crop Protection Council, 8th Edition (1987): forexample pages 491 to 492 (ISOPROTURON), page 538 (METHABENZTHIAZURON)and pages 573 to 574 ( METRIBUZINE).

The heteroaryloxyacetamides of the formula (I) which are defined undergroup (1) act preferentially against monocotyledon weeds (=grass weeds)but additionally act against some dicotyledon weeds.

The active ingredients mentioned under group (2) can be used forselectively combatting a broad spectrum of weeds and grass weeds ineconomically important cultures, such as, for example, cereals, maize,soya bean, cotton, beet and rice. However, their action against certainmonocotyledon and dicotyledon weeds is not always adequate. Importantproblem weeds, such as, for example, Galium aparine or Lolium species,are frequently only insufficiently combatted.

It has now been found, surprisingly, that the active ingredientcombinations defined above and consisting of the heteroaryloxyacetamidesof the formula (I) or group (1) and the active ingredients mentionedunder group (2) have a particularly high activity and can be selectivelyused in many cultures.

Surprisingly, the herbicidal activity of the active ingredientcombination according to the invention is substantially higher than thesum of the actions of the individual active ingredients.

There is thus an unforeseeable genuine synergistic effect present andnot just an additive effect. The novel active ingredient combinationsare well tolerated in many cultures, the novel active ingredientcombinations also readily combatting weeds which are otherwise difficultto combat, such as Galium aparine and Lolium species. The novel activeingredient combinations thus represent a valuable enrichment of theselective herbicides.

The active ingredient combinations according to the invention can beused, for example, in connection with the following plants:

Dicotyledon weeds of the genera: Sinapis, Lepidium, Galium, Stellaria,Matricaria, Anthemis, Galinsoga, Chenopodium, Urtica, Senecio,Amaranthus, Portulaca, Xanthium, Convolvulus, Ipomoea, Polygonum,Sesbania, Ambrosia, Cirsium, Carduus, Sonchus, Solanum, Rorippa, Rotala,Lindernia, Lamium, Veronica, Abutilon, Emex, Datura, Viola, Galeopsis,Papaver, Centaurea, Trifolium, Ranunculus and Taraxacum.

Dicotyledon cultures of the genera: Gossypium, Glycine, Beta, Daucus,Phaseolus, Pisum, Solanum, Linum, Ipomoea, Vicia, Nicotiana,Lycopersicon, Arachis, Brassica, Lactuca, Cucumis and Cucurbita.

Monocotyledon weeds of the genera: Echinocholoa, Setaria, Panicum,Digitaria, Phleum, Poa, Festuca, Eleusine, Brachiaria, Lolium, Bromus,Avena, Cyperus, Sorghum, Agropyron, Cynodon, Monochoria, Fimbristylis,Sagittaria, Eleocharis, Scirpus, Paspalum, Ischaemum, Sphenoclea,Dactyloctenium, Agrostis, Alopercuru and Apera.

Monocotyledon weeds of the genera: Oryza, Zea, Triticum, Hordeum, Arena,Secale, Sorghum, Panicum, Saccharum, Ananas, Asparagus and Allium.

However, the use of the active ingredient combinations according to theinvention is in no way restricted to these genera, but also extends inthe same manner to other plants.

The synergistic effect of the active ingredient combination according tothe invention is particularly pronounced at certain concentrations.However, the weight ratios of the active ingredients and the activeingredient combinations can be varied within relatively wide ranges. Ingeneral, 0.001 to 1,000 parts by weight, preferably 0.01 to 100 parts byweight, particularly preferably 0.1 to 30 parts by weight of activeingredient of group (2) are used per 1 part by weight of activeingredient of group (1) formula (I).

The active ingredients or active ingredient combinations can beconverted into the customary formulations, such as solutions, emulsions,wettable powders, suspensions, powders, dusting agents, pastes, solublepowders, granules, suspension-emulsion concentrates, natural andsynthetic materials impregnated with active ingredient, and very finecapsules in polymeric substance.

These formulations are produced in a known manner, for example by mixingthe active ingredients with extenders, that is liquid solvents and/orsolid carriers, optionally with the use of surface-active agents, thatis emulsifying agents and/or dispersing agents and/or foam-formingagents.

In the case of the use of water as an extender, organic solvents can,for example, also be used as auxiliary solvents. As liquid solvents,there are suitable in the main: aromatics, such as xylene, toluene oralkylnaphthalenes, chlorinated aromatics and chlorinated aliphatichydrocarbons, such as chlorobenzenes, chloroethylenes or methylchloride, aliphatic carbons, such as cyclohexane or paraffins, forexample petroleum fractions, mineral and vegetable oils, alcohols, suchas butanol or glycol, as well as their ethers and esters, ketones, suchas acetone, methyl ethyl ketone, methyl isobutyl ketone andcyclohexanone, strongly polar solvents, such as dimethylformamide anddimethyl sulphoxide, as well as water.

As solid carriers there are suitable: for example, ammonium salts andground natural minerals, as kaolins, clays, talc, chalk, quartz,attapulgite, montmorillonite or diatomaceous earth, and ground syntheticminerals, such as finely divided silica, alumina and silicates; as solidcarriers for granules there are suitable: for example, crushed andfractionated natural rocks such as calcite, marble, pumice, sepioliteand dolomite, as well as synthetic granules of inorganic and organicmeals, and granules of organic material such as sawdust, coconut shells,maize cobs and tobacco stalks; as emulsifying and/or foam-forming agentsthere are suitable: for example, nonionic and anionic emulsifiers, suchas polyoxyethylene fatty acid esters, polyoxyethylene fatty alcoholethers, for example alkylaryl polyglycol ethers, alkylsulphonates,alkylsulphates, arylsulphonates as well as albumen hydrolysis products;as dispersing agents there are suitable: for example, lignin-sulphitewaste liquors and methylcellulose.

Adhesives such as carboxymethylcellulose and natural and syntheticpolymers in the form of powders, granules or latexes, such as gumarabic, polyvinyl alcohol and polyvinyl acetate, as well as naturalphospholipids, such as cephalins and lecithins, and syntheticphospholipids, can be used in the formulations. Further possibleadditives are mineral and vegetable oils.

It is possible to use colorants such as inorganic pigments, for exampleiron oxide, titanium oxide and Prussian blue, and organic dyestuffs,such as alizarin dyestuffs, azo dyestuffs and metal phthalocyaninedyestuffs, and trace nutrients such as salts of iron, manganese, boron,copper, cobalt, molybdenum and zinc.

The formulations contain in general between 0.1 and 95% by weight ofactive ingredient combination, preferably between 0.5 and 90%.

The active ingredient combinations according to the invention are usedin general in the form of finished formulations. However, the activeingredients contained in the active ingredient combinations can also bemixed in the form of individual formulations during use, that is to saythey can be used in the form of tank mixes.

The novel active ingredient combinations, as such or in the form oftheir formulations, can furthermore be used as a mixture with otherknown herbicides, once again finished formulations or tank mixes beingpossible. A mixture with other known active ingredients, such asfungicides, insecticides, acaracides, nematicides, bird repellents,growth substances, plant nutrients and agents which improve soilstructure, is also possible. For certain intended uses, in particular inthe postemergence method, it may furthermore be advantageous to includeplant-tolerated mineral or vegetable oils (for example the commercialpreparation "Oleo Dupont 11E") or ammonium salts, such as, for example,ammonium sulphate or ammonium thiocyanate, as further additives in theformulations.

The novel active ingredient combinations can be used as such, in theform of their formulations or in the use forms prepared therefrom byfurther dilution, such as ready-to-use solutions, suspensions,emulsions, powders, pastes and granules. They are used in the customarymanner, for example by watering, spraying, atomising, dusting orscattering.

The application rates of the active ingredient combinations according tothe invention can be varied within a certain range; they depend, interalia, on the weather and on the soil factors. In general, theapplication rates are between 0.01 and 10 kg per ha, preferably between0.05 and 5 kg per ha, particularly preferably between 0.1 and 3.0 kg perha.

The active ingredient combinations according to the invention can beapplied before or after emergence of the plants, that is to say by thepreemergence or postemergence method.

The good herbicidal action of the novel active ingredient combinationsis evident from the Examples below. While the individual activeingredients have weaknesses in the herbicidal action, the combinationsall exhibit a very good action against weeds, over and above a simplesummation of actions.

Herbicides have a synergistic effect whenever the herbicidal action ofthe active ingredient combination is greater than that of the individualactive ingredients applied.

The action to be expected for a given combination of two herbicides canbe calculated as follows (cf. COLBY, S. R.; "Calculating synergistic andantagonistic responses of herbicide combinations", Weeds 15, pages20-22, 1967):

    ______________________________________                                        If   X =    % damage by herbicide A (active ingredient of                                 group 1) at an application rate of p kg/ha and                         Y =    % damage by herbicide B (active ingredient of                                 group 2) at an application rate of p kg/ha and                         E =    the expected damage by herbicides A and B at an                               application rate of p and q kg/ha,                                then E = X + Y - (X · Y/100).                                        ______________________________________                                    

If the actual damage is greater than calculated, the combination issuperadditive in its effect, that is to say it exhibits a synergisticeffect.

The Examples which follow show that the herbicidal action found for theactive ingredient combinations according to the invention in the weedsis greater than the calculated action, that is to say the novel activeingredient combinations have a synergistic effect.

USE EXAMPLES

For the preparation of the active ingredient formulations required forthe tests, corresponding amounts of a water-dispersible powderformulation (WP) of the heteroaryloxyacetamide of the formula (I-1 ) anda commercial formulation of the active ingredient of group 2 are weighedand are diluted with water to the desired concentration; differentcombinations of the two active ingredients were prepared by mixing.

A 70 % strength WP was used as a METHABENZTHIAZURON formulation (tradename: ®TRIBUNIL, Bayer AG).

50% strength WG (water-dispersible granules) were used as an ISOPROTURONformulation (trade name: ®ARELON, Hoechst AG).

A 70% strength WP was used as a METRIBUZINE formulation (trade name:®SENCOR, Bayer AG).

The tests were carried out as follows:

A) Preemergence tests/Greenhouse

Seeds of the test plants are sown in standard soil and, after 24 hours,are watered with the active ingredient formulation. The amount of waterper unit area is advantageously kept constant. The active ingredientconcentration in the formulation plays no role, only the applicationrate of the active ingredient per unit area is decisive. After thetreatment, the test plants are kept in a greenhouse house undercontrolled conditions (temperature, atmospheric humidity, light) untilthe evaluation.

After 3 weeks, the degree of damage to the plants is rated in % damagein comparison with the development of untreated control plants.

The figures have the following meaning:

    ______________________________________                                        0 =      No effect/damage (like untreated control)                            100 =    Total destruction                                                    ______________________________________                                    

Postemergence tests/Greenhouse

Test plants which have reached a height of 5 to 15 cm are sprayed withthe active ingredient formulations so that the amounts of activeingredient desired in each case are applied per unit area. Theconcentration of the spray liquors is chosen so that the amounts ofactive ingredient desired in each case are applied in 500 l of water perha. After the treatment, the test plants are kept in a greenhouse undercontrolled conditions (temperature, atmospheric humidity, light) untilthe evaluation. After three weeks, the degree of damage to the plants israted in % damage in comparison with the development of the untreatedcontrol plants.

The figures have the following meaning:

    ______________________________________                                        0 =      No effect/damage (like untreated control)                            100 =    Total destruction                                                    ______________________________________                                    

Active ingredients, application rates and results are shown in theTables below, the abbreviations used in the Tables having the followingmeanings:

    ______________________________________                                        (I-1) =    N-Isopropyl-N-(4-fluorophenyl)-(5-tri-                                        fluoromethyl-1,3,4-thiadiazol-2-yloxy)-                                       acetamide;                                                         (IPU) =    ISOPROTURON;                                                       (MBT) =    METHABENZTHIAZURON;                                                (MBZ) =    METRIBUZINE;                                                       Found =    Damage or action found (in percent);                               Calc. =    Damage or action calculated using the                                         above COLBY formula (in percent).                                  ______________________________________                                    

                  TABLE A-1                                                       ______________________________________                                        Preemergence test/Greenhouse                                                  Active ingredient                                                                        Application rate                                                                          Test plants                                            or active  g/ha        Damage or action in %                                  ingredient (Active     Wheat      Galium                                      combination                                                                              ingredient) Found   Calc.                                                                              Found Calc.                               ______________________________________                                        (I-1)        125       10           70                                        Known                                                                         (MBT)      1,500        0           20                                        Known                                                                         (I-1) + (MBT)                                                                            125 + 1,500 10      10   95    76                                  According to the                                                              invention                                                                     ______________________________________                                    

                  TABLE A-2                                                       ______________________________________                                        Preemergence test/Greenhouse                                                  Active ingredient                                                                        Application rate                                                                          Test plants                                            or active  g/ha        Damage or action in %                                  ingredient (Active     Wheat      Alopecurus                                  combination                                                                              ingredient) Found   Calc.                                                                              Found Calc.                               ______________________________________                                        (I-1)      125         10           90                                        Known                                                                         (MBT)      750         0            20                                        Known      1,500       0            70                                        (I-1) + (MBT)                                                                            125 + 750   10      10   100   92                                  According to the                                                                         125 + 1,500 10      10   100   97                                  invention                                                                     ______________________________________                                    

                  TABLE A-3                                                       ______________________________________                                        Preemergence test/Greenhouse                                                  Active ingredient                                                                        Application rate                                                                          Test plants                                            or active  g/ha        Damage or action in %                                  ingredient (Active     Wheat      Lolium                                      combination                                                                              ingredient) Found   Calc.                                                                              Found Calc.                               ______________________________________                                        (I-1)        125       10           60                                        Known                                                                         (MBT)      1,500        0           40                                        Known                                                                         (I-1) + (MBT)                                                                            125 + 1,500 10      10   90    76                                  According to the                                                              invention                                                                     ______________________________________                                    

                  TABLE B-1                                                       ______________________________________                                        Postemergence test/Greenhouse                                                 Active ingredient                                                                        Application rate                                                                          Test plants                                            or active  g/ha        Damage or action in %                                  ingredient (Active     Barley     Matricaria                                  combination                                                                              ingredient) Found   Calc.                                                                              Found Calc.                               ______________________________________                                        (I-1)      125         30           50                                        Known                                                                         (MBT)      125         0            80                                        Known                                                                         (I-1) + (MBT)                                                                            125 + 125   0       30   100   90                                  According to the                                                              invention                                                                     ______________________________________                                    

                  TABLE B-2                                                       ______________________________________                                        Postemergence test/Greenhouse                                                 Active ingredient                                                                        Application rate                                                                          Test plants                                            or active  g/ha        Damage or action in %                                  ingredient (Active     Wheat      Avena                                       combination                                                                              ingredient) Found   Calc.                                                                              Found Calc.                               ______________________________________                                        (I-1)      125         0            50                                        Known                                                                         (MBT)      500         0            10                                        Known      1,000       0            30                                        (I-1) + (MBT)                                                                            125 + 500   10      0    98    55                                  According to the                                                                         125 + 1,000 10      0    98    65                                  invention                                                                     ______________________________________                                    

                  TABLE A-4                                                       ______________________________________                                        Preemergence test/Greenhouse                                                  Active ingredient                                                                        Application rate                                                                          Test plants                                            or active  g/ha        Damage or action in %                                  ingredient (Active     Wheat      Galium                                      combination                                                                              ingredient) Found   Calc.                                                                              Found Calc.                               ______________________________________                                        (I-1)        125       10           70                                        Known                                                                         (IPU)        500       0            0                                         Known      1,000       10           0                                                    2,000       10           20                                        (I-1) + (IPU)                                                                            125 + 500   0       10   80    70                                  According to the                                                                         125 + 1,000 0       19   90    70                                  invention  125 + 2,000 10      19   90    76                                  ______________________________________                                    

                  TABLE B-3                                                       ______________________________________                                        Postemergence test/Greenhouse                                                 Active ingredient                                                                        Application rate                                                                          Test plants                                            or active  g/ha        Damage or action in %                                  ingredient (Active     Barley     Sinapis                                     combination                                                                              ingredient) Found   Calc.                                                                              Found Calc.                               ______________________________________                                        (I-1)      125         30           40                                        Known                                                                         (IPU)      125          0           70                                        Known                                                                         (I-1) + (IPU)                                                                            125 + 125   0       30   100   82                                  According to the                                                              invention                                                                     ______________________________________                                    

                  TABLE B-4                                                       ______________________________________                                        Postemergence test/Greenhouse                                                 Active ingredient                                                                        Application rate                                                                          Test plants                                            or active  g/ha        Damage or action in %                                  ingredient (Active     Wheat      Avena                                       combination                                                                              ingredient) Found   Calc.                                                                              Found Calc.                               ______________________________________                                        (I-1)      125         0            50                                        Known                                                                         (MBZ)       30         0            20                                        Known                                                                         (I-1) + (MBZ)                                                                            125 + 30    10      0    90    60                                  According to the                                                              invention                                                                     ______________________________________                                    

                  TABLE B-5                                                       ______________________________________                                        Postemergence test/Greenhouse                                                 Active ingredient                                                                        Application rate                                                                          Test plants                                            or active  g/ha        Damage or action in %                                  ingredient (Active     Maize      Abutilon                                    combination                                                                              ingredient) Found   Calc.                                                                              Found Calc.                               ______________________________________                                        (I-1)      250         0             0                                        Known      500         0            10                                        (MBZ)       30         0            30                                        Known                                                                         (I-1) + (MBZ)                                                                            250 + 30    0       0    100   30                                  According to the                                                                         500 + 30    0       0    100   37                                  invention                                                                     ______________________________________                                    

                  TABLE B-6                                                       ______________________________________                                        Postemergence test/Greenhouse                                                 Active ingredient                                                                        Application rate                                                                          Test plants                                            or active  g/ha        Damage or action in %                                  ingredient (Active     Maize      Chenopodium                                 combination                                                                              ingredient) Found   Calc.                                                                              Found Calc.                               ______________________________________                                        (I-1)      250         0            30                                        Known      500         0            30                                        (MBZ)       30         0            30                                        Known                                                                         (I-1) + (MBZ)                                                                            250 + 30    0       0    100   51                                  According to the                                                                         500 + 30    0       0    100   51                                  invention                                                                     ______________________________________                                    

                  TABLE B-7                                                       ______________________________________                                        Postemergence test/Greenhouse                                                 Active ingredient                                                                        Application rate                                                                          Test plants                                            or active  g/ha        Damage or action in %                                  ingredient (Active     Maize      Solanum                                     combination                                                                              ingredient) Found   Calc.                                                                              Found Calc.                               ______________________________________                                        (I-1)      250         0            10                                        Known      500         0            20                                        (MBZ)       60         0            60                                        Known                                                                         (I-1) + (MBZ)                                                                            250 + 60    10      0    100   64                                  According to the                                                                         500 + 60    10      0    100   68                                  invention                                                                     ______________________________________                                    

                  TABLE B-8                                                       ______________________________________                                        Postemergence test/Greenhouse                                                 Active ingredient                                                                        Application rate                                                                          Test plants                                            or active  g/ha        Damage or action in %                                  ingredient (Active     Maize      Setaria                                     combination                                                                              ingredient) Found   Calc.                                                                              Found Calc.                               ______________________________________                                        (I-1)      250         0             60                                       Known                                                                         (MBZ)       60         0            40                                        Known                                                                         (I-1) + (MBZ)                                                                            250 + 60    0       0    100   76                                  According to the                                                              invention                                                                     ______________________________________                                    

                  TABLE B-9                                                       ______________________________________                                        Postemergence test/Greenhouse                                                 Active ingredient                                                                        Application rate                                                                          Test plants                                            or active  g/ha        Damage or action in %                                  ingredient (Active     Maize      Digitaria                                   combination                                                                              ingredient) Found   Calc.                                                                              Found Calc.                               ______________________________________                                        (I-1)      125         10            80                                       Known      250         10           80                                        (MBZ)       30         10           20                                        Known                                                                         (I-1) + (MBZ)                                                                            125 + 30     0      19   100   84                                  According to the                                                                         250 + 30    10      19   100   84                                  invention                                                                     ______________________________________                                    

We claim:
 1. A herbicidal composition comprising (1) N-isopropyl-N-(4-fluorophenyl)-5-trifiuoromethyl-1, 3, 4-thiadiazol-2-yl oxy)-acetamide and (2) a synergistically effective amount of metribuzine.
 2. A composition according to claim 1, wherein the ratio of (1):(2) is from 1:0.01 to 1:100.
 3. A composition according to claim 1, wherein the ratio of (1):(2) is from 1:0.1 to 1:30.
 4. A composition according to claim 1, wherein the ratio of (1):(2) is 125:30.
 5. A composition according to claim 1, wherein the ratio of (1):(2) is 250:30.
 6. A composition according to claim 1, wherein the ratio of (1):(2) is 500:30.
 7. A method of combating weeds in the growing of a crop which comprises applying to such weeds, to the crop or to the soil in which said crop is growing or to be grown a selectively herbicidally effective amount of a composition according to claim
 1. 8. The method according to claim 7, wherein such crop is soybeans.
 9. The method according to claim 7, wherein such crop is corn.
 10. The method according to claim 9, wherein the ratio of (1):(2) is 1:0.1 to 1:30. 